The three Digit Counter described on this page uses a 3-Digit BCD Counter ,CMOS CD14553 ,addressing a 3-Digit decoder/driver ,CMOS 14543 . It uses the multiplexing method of addressing the displays segments and needs three PNP transistors to either source or sink the current of each transistor serially activated by a signal from pins 1,2 and 15 of the 14553 .

The MC14553 by Motorola contains three counters . The information is timed/division multiplexed providing one BCD number or digit at a time , This process is done by an on board 100kHz oscillator and the frequency is set by the .001uF capacitor connected between pins 3 and 4 .

The circuit on the rightis designed to drive Common Cathode Displays.

It can be made to drive Common Anode Displays with the following modifications.

a ) Change the connectionfrom pin #6 of the 14543 IC from the NEG. to the POS. bus

A suggested layout is shown below , it is strongly advised that IC sockets be used . Where the Rs resistors are shown 14 pin dip sockets can be inserted and the resistors can be inserted in the socket if preferred which will allow for change of Rs value if required .
The Layout and PCB provide for the modification to Common Anode by simply moving the jumpers ( in red ) from pin 6 to + or - as well as for the emitters/collectors connections as explained above .

PCB layout
is actual size

As with the previous counter common anode and large displays can be used but first , modifications to the circuit as described above must be made .
For details see Shuffle board .